Do intermediate muscle (via) points & muscle wrappers exert forces on the bodies they are connected to?

[Pasha van Bijlert]

Hello,

The title says it all - I'm wondering if (and since I expect yes, how) intermediate muscle points exert forces on the bodies they are connected to.

For a concrete example: Let's say you were to model the gastrocnemius with three points; an origin on the femur body, a fixed point on the tibia body, and then the insertion on the calcaneus (foot body). When there is a force in the muscle, is a reaction force from the middle point applied to the tibia (and vice versa)? I would expect that reaction forces ensure the path point stays in its place, but I tried checking the OpenSim & Simbody documentations and I couldn't find how these are treated.

Cheers,
Pasha

[Matthew Lee]

Hi Pasha,

You can try this plugin,https://simtk.org/projects/force_direction I hope this tool could help you.

Best Wishes,
Matthew